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MAXAMP

A collimating element that sets the maximum transmitted particle amplitudes for all following elements, until the next MAXAMP.
Parallel capable? : yes
Parameter Name Units Type Default Description
X_MAX $M$ double 0.0 x half-aperture
Y_MAX $M$ double 0.0 y half-aperture
ELLIPTICAL   long 0 is aperture elliptical?
EXPONENT   long 2 exponent for boundary equation in elliptical mode. 2 is a true ellipse.
YEXPONENT   long 0 y exponent for boundary equation in elliptical mode. If zero, defaults to EXPONENT.
OPEN_SIDE   STRING NULL which side, if any, is open (+x, -x, +y, -y)
GROUP   string NULL Optionally used to assign an element to a group, with a user-defined name. Group names will appear in the parameter output file in the column ElementGroup





This element sets the aperture for itself and all subsequent elements. The settings are in force until another MAXAMP element is seen.

This can introduce unexpected behavior when beamlines are reflected. For example, consider the beamline

...
L1:  LINE=( ... )
L2:  LINE=( ... )
MA1: MAXAMP,X_MAX=0.01,Y_MAX=0.005
MA2: MAXAMP,X_MAX=0.01,Y_MAX=0.002
BL1: LINE=(MA1,L1,MA2,L2)
BL:  LINE=(BL1,-BL1)

This is equivalent to

BL:  LINE=(MA1,L1,MA2,L2,-L2,MA2,-L1,MA1)
Note that the aperture MA1 is the aperture for all of the first instance of beamline L1, but that MA2 is the aperture for the second instance, -L1. This is probably not what was intended. To prevent this, it is recommended to always use MAXAMP elements in pairs:
BL1: LINE=(MA2,MA1,L1,MA1,MA2,L2)
BL:  LINE=(BL1,-BL1)
which is equivalent to
BL:  LINE=(MA2,MA1,L1,MA1,MA2,L2,-L2,MA2,MA1,-L1,MA1,MA2)
Now, both instances of L1 have the aperture defined by MA1 and both instances of L2 have the aperture defined by MA2.
next up previous
Next: MBUMPER Up: Element Dictionary Previous: MATTER
Robert Soliday 2014-03-21